Paul Gray died from an overdose

An autopsy has proven that Slipknot's bassist Paul Gray died from an accidental overdose after taking morphine and fentanyl

Paul Gray died from an accidental overdose, autopsy results have proved.

The bassist for band Slipknot is thought to have taken morphine and fentanyl - an imitation of morphine - when he died.

The musician's body was found in a Des Moines hotel room last month, reportedly close to a hypodermic needle and scattered pills.

It is not yet known where he got the drugs from.

A police spokesperson, Sgt. Dave Disney said there is "no evidence" he was prescribed the drugs by a doctor.

The autopsy is also believed to have shown the bassist suffered from heart disease.

Speaking at the time of Paul's death, Neil Portnow - President of the Recording Academy, which runs the Grammys - said: "The heavy metal world has lost an immense talent, and Slipknot's loyal following will ensure he, and his music, are remembered for years to come."

Slipknot were famously known for wearing ghoulish masks on stage and Paul was also the co-founder for the group.